A2: Microbes in the News

Scientists Turn Food Poisoning Microbe into Powerful Cancer Fighter

Michael Price, 2/8/17, Science Magazine



Summary: Scientists have found a way to modify the bacteria Salmonella in order to trigger an immune response in the body to fight off cancer cells. They tested this by implanting human cancer cells in mice and the bacteria actually shrunk the tumors and prevented the cancer cells from spreading to other parts of the body. Salmonella is a rod-shaped bacteria that causes food poisoning. It was genetically modified to secrete the protein known as FlaB. In one experiment, 20 mice were injected with human colon cancer cells and then injected with the bacteria. Three days later, the mice had cleared all of the bacteria from their body except for their colons, which were crawling with Salmonella. After 120 days, the tumors were gone in 11 of the 20 mice.


Connections: This article shows just how important microbes are in our every day life. With all that we have learned about them, we can do so much to manipulate and use them to our advantage.


Critical Analysis: Everything about the fight against cancer fascinates me. It is such a strong disease to have and so much has been done to try and fight it. This article is really interesting to me because it seems like it could really work. However, this study was only done on mice and I really want to know how it would actually affect humans. The author didn’t cover exactly how this bacteria was fighting the cancer cells so I wish they would’ve gone into more depth about that part of it. Overall, this article was easy to read and did a great job at conveying information to the reader.


Question: I would like to know how the Salmonella bacteria could be used to fight cancer cells, but how it doesn’t affect the normal cells of the body? Is it possible for a bacteria to interpret which one is which?

A2: Microbes in the News

Article title: Scientists turn food poisoning microbe into powerful cancer fighter

Date: Feb 8, 2017

Author :Michael Price

Source: Science

Link: https://www.sciencemag.org/news/2017/02/scientists-turn-food-poisoning-microbe-powerful-cancer-fighter


Assignment author: Morgen Southwood



Cancer cells are not attacked by our immune system because they are considered to be ‘self.’ There has been some successful research into marking cancer cells for immune system attacks through the use of bacteria. One such treatment for bladder cancer is already approved by the FDA. Bacteria can target cancer cells because they tend to be necrotic and oxygen depleted, which is the kind of weekend tissue pathogens naturally target.     This article focuses on a study on the use of Salmonella. In mouse studies it has been found to eliminate/reduce tumors, and even help prevent secondary tumor formation from human colon cancer metastases injected into mice. The Salmonella used in the studies was altered to produce FlaB which is the protein the spurs the elevated immune responses.


This article strongly related to the lectures we are having on immunity. One element of the lectures that is particularly relevant is the way that the immune system has an amplified response the second time it encounters an antigen, and the specificity of antigen identification. From what I understand, this treatment would only deal with tumors that are present as long as the altered Salmonella is present. Since the Immune system is attacking Salmonella, and hasn’t been taught that the cancer cells were the danger all along, this treatment can not cure or prevent future cancers.

Critical analysis-

I really enjoyed the level of detail that this article went into, it described relevant methods and results in a clear and concise manner. I think the terminology used, the explanations provided made this article accessible and informative for the public. What I learned from this article is the targeting mechanism involved in bacterial cancer treatment. I find it very interesting that bacteria can be so relied upon to target the necrotic oxygen depleted cancer cells, and not healthy ones.  One thing I noticed in this treatment is that it has a narrow application. This is not the cure for cancer, it is only one more weapon. I do not this this treatment could be used on an immune compromised person, or on cancers that have morphological of physiological characteristics that cant be targeted by bacteria.


They have performed an experiment where they injected colon cancer cells into 20 mice. They used the treatment on half of them and observed them for 120 days to see if the cancer remained. In the next experiment they injected metastasizing colon cancer cells into six mice and after 27 days the six treatment mice and 7 control mice were examined for tumors. Briefly, describe what the next experiment on this treatment should entail.